Carl Holtje


As portable computing devices grow in popularity, so does the need for secure communications. Lacking tethers, these devices are ideal for forming small proximal groups in an ad-hoc fashion in environments where no server or permanent services are available. Members of these groups communicate over a broadcast or multicast network interconnect, and rely upon each other to form a cohesive group. While generally small in size and short in lifetime, security is a critical aspect of these groups that has received much academic attention in recent years. Much of the research focuses upon generating a common, group-wide private key suitable for encryption. This group key agreement utilizes keying technology that is very costly for small, limited-lifetime devices. Furthermore, key agreement provides no constructs for message authentication or integrity. Traditional systems require two keypairs to address both aspects of the secure group and one for encryption, the other for message validation. This work investigates the appropriateness of using a shared keypair for both contributory group key agreement and message quality guarantees. A JCE-compliant key agreement and digital signature framework has been implemented and is presented, and discussed. Using elliptic curve-based keys, this is possible at no loss in security, and these keys are easily and quickly computable on smaller devices. Algorithms that are known for their cryptographic strength are leveraged in both encryption and digital signature applications. This technique provides a computationally-effient key agreement scheme and digital signature framework, and a network-effcient key and signature distribution system. Perfect forward and backward security is maintained, and all members retain a current view of the group from a cryptographic perspective. This thesis is the culmination of several quarters of research and work, all conducted at the Rochester Institute of Technology under the supervison of Dr. Hans-Peter Bischof between December 2002 and January 2004. This thesis is completed as partial fullfillment of the requirements for a Masters Degree in Computer Science from the Rochester Institute of Technology.

Library of Congress Subject Headings

Computer networks--Security measures; Data encryption (Computer science); Portable computers; Cluster analysis

Publication Date


Document Type


Department, Program, or Center

Computer Science (GCCIS)


Bischof, Hans-Peter

Advisor/Committee Member

Hemaspaandra, Edith

Advisor/Committee Member

White, Phil


Note: imported from RIT’s Digital Media Library running on DSpace to RIT Scholar Works. Physical copy available through RIT's The Wallace Library at: TK5105.59 .H65 2004


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